Invasion of an alien freshwater crayfish is newly confirmed in Madagascar. The invasive crayfish is determined as the parthenogenetic Marmorkrebs (marbled crayfish) (Cambaridae: Decapoda) on the basis of morphological features and the fact that all collected specimens were females regardless of their size. As this is a worrisome finding, the public should be alerted so that spread on the island can be prevented before it affects the vulnerable native crayfish biodiversity and the rice field business in Madagascar.

(Note: What the abstract does not mention is that this paper contains the first detailed description of Marmorkrebs morphology. This should greatly aid identifications, since many species of Procambarus superficially resemble Marmorkrebs, particularly in the marbled colouration.)

This was fun and interesting in a few ways. At the suggestion of the organizer, my student Stephanie and I gave a joint talk, which isn’t all that common. I did the first third, she did the middle, and I returned to handle the last third.

We also left the audience wondering how we got PowerPoint to do all the zooming. The answer was that we didn’t use PowerPoint for our visual aids. Instead, we were experimenting with some new software called Prezi. If you do presentations, you probably have a few months where it’ll be really cool before everyone else discovers it.

The biggest surprise was that a couple of audience members had direct ties to Marmorkrebs. One sold them in Switzerland back in the 1990s. Another confirmed something that I’ve only heard as a rumour, namely that Marmorkrebs are being aquacultured in China. More to follow on these leads, no doubt.

Thanks very much to everyone in these pictures for coming to our talk!

15 September 2009

I was re-reading the recent paper on the introduction of Marmorkrebs in Italy (Marzano et al., 2009), and noticed this:

In their publication on (sic) Nature, the authors even raised the hypothesis that Procambarus sp. is a transgenic species created by laboratories in Hong Kong.

The only Nature paper featuring Marmorkrebs to date is the first one (Scholtz et al., 2003). I freely admit that I miss things, and do not remember everything. But the paper is only one page, so a statement like that would be hard to miss. And I’d like to think I would have remembered a claim that Marmorkrebs were the result of a scientific experiment gone wrong.

I re-read the Nature paper. The words, “Hong Kong” do not appear in it. There is a brief mention of transgenics, but it is in a comment saying that Marmorkrebs would be good for transgenic experiments in the future, not that they were the result of transgenic experiments in the past. For a moment, I wondered in the reference cited (Nam et al., 2000) next to the comment about Marmorkrebs’ potential was from a Hong Kong lab, but the authors of that paper all gave South Korea as their country of origin.

The origin of this comment is almost as puzzling at the origins of Marmorkrebs itself.

Marmorkrebs already sound like they’ve stepped straight out from a science fiction potboiler. You cannot work with an invasive species of female clones (which Marmorkrebs is) without at least thinking of old monster movies or pulp magazines. If they were truly an escaped science experiment? And “made in Hong Kong” to boot? Forget my next grant proposal... I’m going to work on my screenplay.

08 September 2009

The always articulate Olivia Judson looks at genome projects in her recent New York Times column, and asks what organisms should be on the list to have their genome sequenced. She makes a persuasive case for the famous “living fossil,” the deep sea coelacanth.

The reader comments contain many good nominees (whales, naked mole rats, potato blight, and more), but I’m afraid I was not selfless. I wrote in the comments:

Coelacanth is an excellent choice. It could be difficult to get enough tissue, given that they are such elusive creatures.

I want to argue for a crayfish genome.

Crayfish (and their relatives, lobsters and other decapod crustaceans) are commercially important. They are harvested for food and cause ecological and economic damages as invasive species to name just two reasons.

Crayfish are important model organisms for research, particularly neurobiology. Discoveries made in crayfish include electrical synapses, presynaptic inhibition, and neuromodulation of aggression.

Crayfish are the current record holder for highest number of chromosomes in an animal (Pacifastacus leniusculus: 2n=376).

There is only one crustacean genome (a small freshwater one, Daphnia pulex). In comparison, about a dozen insect genomes are complete and more are on the way.

Probably the best choice of species would be Louisiana red swamp crayfish (Procambarus clarkii), because it is common, spread across the globe, and well studied.

The mysterious crayfish Marmorkrebs could be an interesting second choice, because their origins are unknown, and they are the only known decapod crustacean where all the individuals are female.